I've actually run a dungeon that had no fighting. It was mainly an experiment where fights were mainly replaced by traps. It was okay, though I think a few puzzles should've been added to it as well.
They work and honestly sometimes it's nice to be able to talk down enemies, especially wild animal attacks if it's a random encounter. But sometimes you just need to beat the enemies to death too.
Not having combat is fine. My GM and I have come up with multiple very combat-light adventures and dungeons through the years. It's usually a lot of traps and puzzles (and my GM is particularly proud of this one Myst-style puzzle dungeon he has in his portfolio), sometimes it's about getting sapient monsters to agree to let the party get through, and other times it's about sneaking/finding a safe route past threats the party knows they have no chance to beat. But the key is that if there
are enemies, the players always have the
option to engage. They might get their asses kicked, but that's just the consequences of their actions.
My problems with the idea of a mandatory "pacifist" dungeon are that it makes martial classes
even less useful, and it breaks the internal consistency of the world. Having a clear foe in front of you but not being able to even
choose to engage it because "lol, fae king said so" is stupid. And the Undertale inspiration makes it doubly stupid. I played Undertale. I also very quickly realized what it was trying to do (the design of that game is deliberately manipulative) and went for a full genocide run out of sheer spite. Why? Because while the game gave me the
option to be a pacifist and considered it the "best" ending, it also gave me the
option to kill things. And that's what matters. Combat is an integral part of D&D. Some enemies
cannot be negotiated with. That's by design. Trying to make the game "more peaceful" helps no one, because the option to be peaceful has always been there if that's what the GM wanted to do.
Pulling the rug out from under the players is almost never a good idea. It can be good in small, localized doses in order to get the players to think laterally, but it has to be measured very carefully against their frustration about being constrained. To use a videogame example, Half-Life 1 has a section in the mid-game where you drop into an explosives warehouse that's booby-trapped with so many laser mines it looks like a goddamn Pink Floyd concert (a clear and obvious reason why you're limited). You obviously can't use any explosives and you have to be very careful where you shoot. Thankfully, there aren't a lot of enemies around. Mostly a handful of headcrabs that you have to shoot before they trip the mines and blow the entire place sky high. Since that setpiece is relatively short (it's mostly just one huge room that you have to find the exit of) and you get a new toy to play with at the end (the Hive Hand), it was memorable. Now imagine playing an entire game where you're given weapons and tight combat mechanics... but you can't actually
fight anything.
I really wonder what the sales numbers for that shit are going to be. Like the wheelchair-accessible dungeon: I saw a lot of talk but not a lot of play outside of these shills who always say "I ran it for my group last weekend" even though their social media patently shows they were playing videogames from dusk till dawn. Really, I don't know anyone who buys 5e modules anymore.
